The present invention relates to the art of power driven threading machines and, more paticularly, to an attachment adapted to be associated with the machine spindle to provide a power output for driving an auxiliary tool or the like.
Power driven thread cutting machines are of course well known and basically comprise a rotatable chuck assembly for supporting and rotating a workpiece, a tool carriage supporting tools for performing work on the rotating workpiece, and a drive unit for rotating the chuck assembly and thus the workpiece. The chuck assembly generally includes a tubular spindle having an axisof rotation and axially opposite ends, and a plurality of workpiece engaging jaw members supported at opposite ends of the spindle for displacement radially inwardly and outwardly of the spindle axis between closed and opened positions with respect to a workpiece introduced into the spindle. The jaw members on the spindle provide for a workpiece to be gripped at axially spaced apart locations along the length thereof and, in the closed positions of the jaws, the workpiece is held in a centered position coaxial with the spindle. A drive unit is provided for the chuck assembly and, in connection with initiating operation of the threading machine, the jaws are generally pivoted relative to the spindle and into engagement with a workpiece positioned in the spindle, after which the workpiece and chuck assembly are driven together by the drive unit through the jaws. Upon completion of a cutting, reaming and/or threading operation, the direction of the drive is reversed, whereby the jaws move outwardly of the spindle axis to release the workpiece. When the direction of the drive is reversed, the spindle and jaws are capable of being driven as a unit in the reverse direction.
Threading machine spindle and jaw assemblies operable in the foregoing manner are shown, for example in U.S. Pat. Nos. 2,916,290 to Skillin, 3,232,629 to Obear, 3,270,492 to Behnke and 2,890,888 to Damijonaitis, and in copending application Ser. No. 123,719 of James C. Redman filed Nov. 23, 1987 and assigned to the same assignee as the present invention, the disclosure of which application is incorporated herein by reference.
Heretofore, operation of the drive unit in the reverse direction had no utility other than achieving release of the jaws from the workpiece to facilitate removal of the workpiece from the spindle following a cutting, reaming and/or threading operation.